The effects of seaweed extract with manganese application on the growth of lettuce were investigated.The results showed that stem and root width,root length,plant height,leaf number,fresh weight and dry weight increased significantly with the application of seaweed extract,and seaweed extract could promote shoot to uptake more nutrition elements.But seaweed extract with manganese application could not promote the growth of lettuce,and lower accumulation of manganese.Therefore,we suggest that seaweed extract was not used with manganese application.